feat: migrate from Cedar to SpiceDB authorization system

This is a major architectural change that replaces the Cedar policy-based
authorization system with SpiceDB's relation-based authorization.

Key changes:

- Migrate from Rust to Go implementation
- Replace Cedar policies with SpiceDB schema and relationships
- Switch from envoy `ext_authz` with Cedar to SpiceDB permission checks
- Update build system and dependencies for Go ecosystem
- Maintain Envoy integration for external authorization

This change enables more flexible permission modeling through SpiceDB's
Google Zanzibar inspired relation-based system, supporting complex
hierarchical permissions that were difficult to express in Cedar.

Breaking change: Existing Cedar policies and Rust-based configuration
will no longer work and need to be migrated to SpiceDB schema.

2 files changed, 0 insertions, 57 deletions

diff --git a/vendor/backtrace/examples/backtrace.rs b/vendor/backtrace/examples/backtrace.rs
deleted file mode 100644
index 7ff6cd39..00000000
--- a/vendor/backtrace/examples/backtrace.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-use backtrace::Backtrace;
-
-fn main() {
-    println!("{:?}", Backtrace::new());
-}
diff --git a/vendor/backtrace/examples/raw.rs b/vendor/backtrace/examples/raw.rs
deleted file mode 100644
index 95e17dbd..00000000
--- a/vendor/backtrace/examples/raw.rs
+++ /dev/null
@@ -1,52 +0,0 @@
-fn main() {
-    foo();
-}
-
-fn foo() {
-    bar()
-}
-fn bar() {
-    baz()
-}
-fn baz() {
-    print()
-}
-
-#[cfg(target_pointer_width = "32")]
-const HEX_WIDTH: usize = 10;
-#[cfg(target_pointer_width = "64")]
-const HEX_WIDTH: usize = 20;
-
-fn print() {
-    let mut cnt = 0;
-    backtrace::trace(|frame| {
-        let ip = frame.ip();
-        print!("frame #{:<2} - {:#02$x}", cnt, ip as usize, HEX_WIDTH);
-        cnt += 1;
-
-        let mut resolved = false;
-        backtrace::resolve(frame.ip(), |symbol| {
-            if !resolved {
-                resolved = true;
-            } else {
-                print!("{}", vec![" "; 7 + 2 + 3 + HEX_WIDTH].join(""));
-            }
-
-            if let Some(name) = symbol.name() {
-                print!(" - {name}");
-            } else {
-                print!(" - <unknown>");
-            }
-            if let Some(file) = symbol.filename() {
-                if let Some(l) = symbol.lineno() {
-                    print!("\n{:13}{:4$}@ {}:{}", "", "", file.display(), l, HEX_WIDTH);
-                }
-            }
-            println!("");
-        });
-        if !resolved {
-            println!(" - <no info>");
-        }
-        true // keep going
-    });
-}